In the prior art, a TFT-LCD is formed by bonding a TFT array substrate with a color filter substrate, and liquid crystals are dripped between the array substrate and the color filter substrate. Generally, the TFT array substrate comprises a substrate, and a gate metal layer, a gate insulating layer, an amorphous semiconductor layer, a doped semiconductor layer, a source/drain metal layer and a pixel electrode layer are provided on the substrate, and the source/drain metal layer is spaced from the pixel electrode layer by an insulating layer. The gate metal layer comprises the gate electrodes and gate lines of the TFT, the source/drain metal layer comprises the source electrodes, drain electrodes and data lines of the TFT, and the pixel electrode layer comprises pixel electrodes.
Generally, the drain electrodes of the TFT are electrically connected with the pixel electrodes through a via hole which goes through the insulating layer between the source/drain metal layer and the pixel electrode layer. In addition, a gate lead hole and a source/drain lead terminal are provided on the TFT array substrate, and the gate lead hole goes through the layers on the gate metal layer and extends to the gate metal layer, and is used for to the connection between the gate line and an external signal input device to provide electric signals to the gate line, while the source/drain lead terminal extends to the source/drain metal layer and is used for the connection between the data line and the external signal input device to provide electrical signals to the data line.
Currently, usually the manufacturing process of the TFT-LCD array substrate requires at least four patterning processes: the first patterning process forms the gate metal layer, the second patterning process forms the amorphous semiconductor layer, the doped semiconductor layer and the source/drain metal layer, the third patterning process forms a protective layer comprising the via hole, the gate lead hole and the source/drain lead terminal for electrically connecting the drain electrode with the pixel electrode, and the fourth patterning process forms the pixel electrode layer.
However, the number of the patterning processes directly affect the manufacturing costs and yield, thus, the more the patterning processes are, the longer the production period is, the higher the manufacturing cost is, and the lower the yield is. Therefore, how to reduce the number of the patterning processes in the manufacturing process of the TFT-LCD array substrate has been a technical problem to be solved by one skilled in the art.